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    <title>Document</title>
    <script>
        var num = 10
        // num = num + 1   num++
        num = num + 2 //num+=2
        console.log(num);
        var age = 10
        // age += 5 //相当于age=age+5
        // age -= 5 //相当于age=age-5
        age *= 10 //相当于age=age*10
        console.log(age);
    </script>
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